In recent years, OFDMA scheme communication systems have been attracting attention, in which, in order to increase communication system throughput, data is mapped on subcarrier signals (carriers) orthogonal to one another on the frequency axis, and the signals are multiplexed (as multicarrier) and transmitted. In particular, in order to enable more efficient communication, not only (temporal) scheduling assigning a transmission packet preferentially to a mobile station apparatus having a good propagation path state, but also, with attention to a frequency direction, frequency scheduling technique assigning a transmission packet preferentially to a subcarrier having a good propagation path state have been actively studied (for example, see Patent Document 1 and Non-patent Document 1).
In this frequency scheduling technique, upon scheduling, a base station needs to know in advance the propagation path state(frequency characteristics) between the base station and a mobile station apparatus in order to assign transmission packets. Therefore, in an OFDMA-FDD (Frequency Division Duplex) system, the mobile station apparatus measures a propagation path state in a used downlink frequency band and reports the measurement result to the base station on uplink, and based on the information, the base station performs transmission packet scheduling. Further, in an OFDMA-TDD (Time Division Duplex) system, not onlyamethod of reporting information regarding a downlink propagation path state from a mobile station apparatus like an FDD system, but also a method of performing downlink scheduling based on uplink propagation path state using uplink/downlink symmetric property have been studied.
In addition, as a similar technique to report downlink information to a base station by a mobile station apparatus, there is an HSDPA (High Speed Downlink Packet Access) scheme. In this scheme, based on downlink reception quality information reported from a mobile station apparatus, a base station determines a modulation scheme of a signal tobe transmitted to this mobile station apparatus (for example, see Patent Document 2).    Patent Document 1: Japanese Patent Application Laid-Open No. 2002-252619 (p. 5-6)    Patent Document 2: Japanese Patent Application Laid-Open No. 2003-199173 (p. 8, FIG. 5)    Non-patent Document 1: “MC-CDMA scheme using frequency scheduling”, Technical Report of IEICE, RCS2002-129, July 2002, p. 61-66